Relay circuit



Feb. 1, 1944. H, LAMB 2,340,668

RELAY C IRCUI T filled Nov. 27, 1942 Patented Feb. 1, 1944 RELAY CIRCUIT Anthony H. Lamb, Hillside, N. J assignor to Weston Electrical Instrument Corporation, Newark, N. J., a corporation of New Jersey Application November 27, 1942, Serial No. 467,157

3 Claims.

This invention relates to relay circuits and particularly to relay circuits employing sensitive relays of the magnetic contact type that include a solenoid-operated resetting system.

Magnetic contacts are employed in sensitive relays to obtain reliable contact closures when the torque developed by the moving coil is not sufficient to effect a firm engagement of the contacts. Such relays must be reset, i. e., th engaged contacts must be separated, by some force additional to that developed by the current flow established in the moving coil by the variable factor (temperature, illumination, pressure or the like) that controls the relay circuit. Sensitive magnet contact type relays with resetting systems are described and claimed in my prior Patents Nos. 2,014,385 and 2,014,386, and the present invention relates to a solenoid reset" relay of the general type of that illustrated in Figs. 4 to 6 of Patent No. 2,062,915.

An object of the invention is to provide a relay circuit including a solenoid reset type of magnetic contact relay, the circuit including elements that reduce the wear on the parts and preclude excessive heating of the solenoid. An object is to provide a relay circuit including a magnetic contact relay having a solenoid actuated resetting system, and switch mechanism in series with the resetting solenoid that is closed only when the magnetic contacts of the relay are engaged. More specifically, an object is to provide a relay circuit including a solenoid reset type of magnetic contact relay, and a solenoidenergizing circuit having a periodically closed switch in series with a normally open switch that is closed by an engagement of the magnetic contacts of the relay.

These and other objects and advantages of the invention will be apparent from the following specification when taken with the accompanying drawing in which the single view is a circuit diagram of an electrical relay embodying the invention. y

In the drawing, the reference numeral I identifies the moving coil of a sensitive instrument type relay, the coil being pivotally supported in the interpolar gap of a permanent magnet 2 and carrying the pointer or contact arm 3. The magnetic contact system comprises a small rider 4 of soft iron or equivalent magnetic material on the contact arm 3, and relatively fixed, permanent magnet contacts 5, 5'.

The resetting mechanism includes pusher arms 6, 6' carried by the armatures I, 1' that are rocked, upon energization of the solenoid 8,

to move the pusher arms towards each other, and the outer ends of the pusher arms are upturned and fitted with soft sleeves 9, 9 for engagement with the contact arm 3 to separate it from the magnet contacts 5, 5' respectively. The relay and resetting system are shown diagrammatically in the drawing, and appropriate physical constructions for the parts are described and illustrated in my prior Patent No. 2,062,915.

The controlled circuit of the sensitive relay comprises an auxiliary relay H and a power source I2, shown diagrammatically as a battery, that are connected in series with each other and across the contact 5 and contact arm 3 of the sensitive relay. The auxiliary or power relay has a normally open set of contacts Ila. in circuit with a load l3, and a set of normally open contacts Ilb in the energizing circuit of the reset solenoid 8.

The resetting circuit also includes a power source, shown as a battery It, and a switch l5 that is periodically closed by cams or fingers it on the shaft of a mechanical or electrical clock mechanism 11. Switches lib and I5 are series elements in the resetting circuit, and the solenoid 8 can be energized by current source l4 only when both switches are closed. For simplicity of illustration, the drawing does not show a controlled circuit between the second magnet contact 5' and the contact arm 3. When the instrument relay controls a second circuit, the switch contacts llb of the power relay II will be shunted by a normally open switch that is closed upon the energization of the second controlled circuit by the engagement of iron rider 4 of contact arm 3 with the magnet contact 5'.

The operation of the relay circuit is as follows. The moving coil l of the sensitive relay is connected to a circuit, not shown, in which the current flow varies with the particular control factor that is to determine the energization of the load l3. The moving coil I is displaced in accordance with fluctuations of the control factor until it reaches the critical value at which the iron rider 4 on contact arm 3 moves into prox imity to the magnet contact 5, and the contact arm is then drawn into engagement with the contact 5 by magnetic attraction. This closure of contacts 4, 5 completes the energizing circuit of the power relay I I, and its sets of contacts I la, l lb close. The load 13 is energized and the resetting circuit is conditioned for energization upon a closure of the switch IS. The clock mechanism I1 effects periodic closures of the switch l5, and the resetting solenoid B is therefore energized upon the first closure of the switch 55 after the rider 4 engages the contact 5 to energize the power relay II. The instrument relay is reset upon this energization of the solenoid 8, and the relay circuit is thus conditioned for a further control action when the current flow through the coil I reaches a critical control value.

The solenoid 8 is not energized at each pcriodic closure of the switch I5, and unnecessary operation of the resetting mechanism is thereby avoided. solenoid only when a resetting operation is necessary, and this avoids the heating of the solenoid that was characteristic of prior solenoid actuated resetting systems that were periodically ener gized upon each closure of switches.

It is to be understood that the invention is not limited to the particular embodiment herein shown and described, and that various modifications that may occur to those familiar with this art fall within the spirit of my invention as set forth in the following claims.

I claim:

1. In a relay circuit, the combination with a relay including magnetic contacts and a resetting system for said relay including a solenoid; of an energizing circuit for the solenoid of said resetclock-actuated Current is supplied to the resettin ting system, said energizing circuit including a normally open switch in series with a periodically closed switch, and means responsive to a closure of said relay contacts for closing said normally open switch.

2. A relay circuit of the type including a sensisitive instrument type relay having magnetic contacts, and means for resetting said relay upon a closure of said contact, characterized by the fact that said resetting means includes a solenoid in series with two switches, means for pcriodically closing one of said switches, and means responsive to a closure of the relay contacts for closing the second switch.

3. In a relay circuit, the combination with an instrument type relay having magnetic contacts, means comprising a pusher arm and a solenoid for separating said magnetic contacts, and an auxiliary relay including a winding in series with a current source and said contacts, said auxiliary relay having a set of contacts for controlling a load circuit. and a set of normally open contacts, of an energizing circuit for the solenoid of said contact separating means; said energizing circuit comprising a source of current and a periodically closed switch in series with said solenoid and with said set of normally open contacts of the auxiliary relay.

ANTHONY H. LAMB. 

